The present invention relates to disk brakes that apply braking force to a vehicle, for example, an automobile.
In general, a disk brake provided in a vehicle, e.g. an automobile, has a caliper disposed to extend over the outer periphery of a disk in the axial direction of the disk, the disk being rotatable relative to a stationary part of a vehicle, a piston provided at at least one side of the caliper in the axial direction of the disk, and a pair of friction pads that are pressed against both sides of the disk by the piston (for example, see Japanese Patent Application Publication No. 2010-175040).
When the driver of the vehicle, for example, performs a braking operation, the piston is slidingly displaced toward the disk by a hydraulic pressure supplied externally, for example, so that the piston presses the friction pads toward the disk, thereby applying braking force to the disk.
It is desirable for disk brakes to be capable of suppressing brake noise throughout the time from when the friction pads are brand-new until the time to replace them with new ones, for example. It is particularly desirable for disk brakes to be capable of stably suppressing brake noise known as “low pressure brake noise” occurring when the driver places his or her foot on the brake pedal just lightly, i.e. during braking in a low pressure range at which the friction pads start to contact the disk.